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Azollaceae

Small, floating herbs, often forming a mat over still waters, rhizome fine, horizontal, branching alternately to the left and right, bearing small, close leaves and fine, simple roots, protostelic. Leaves +/- imbricate, alternate, bilobed, papillose. Sporangia borne in sporocarps, in the axils of the submerged lobes of the leaves, enclosed in a thin indusium, the sporocarps of 2 types, microsporocarp large, with several microsporangia each with many microspores, megasporocarp with a single megasporangium with a single megaspore; spores globose, trilete.

Distribution

A mongeneric family with about 6 species, found throughout the tropical and temperate regions of the world. Azolla pinnata is the only, and possibly introduced species in Papuasia.

Literature

Croft, J.R. 1985. Azollaceae. In Leach, G.J. & Osborne, P.L., Fresh water plants of Papua New Guinea. Univ. P.N.G., Port Moresby. pp. 36 - 38.

Follieri, M. 1977. Classification and phyllogeny of living and fossil water ferns of the genus "Azolla". Webbia 31: 97 - 104, f. pl. 1 - 2.

Johns, R.J. 1981. The ferns and fern-allies of Papua New Guinea. Part twelve: the Azollaceae. P.N.G. Univ. Tech. Res. Rep. R 48 - 81: 35.1 - 35.3

Lumpkin, T.A. & Plucknett, D.L. 1980. Azolla: botany, physiology, and use as a green manure. Econ. Bot. 34: 111 - 153, f. 1 - 20.

Moore, A.W. 1969. Azolla: biology and agronomic significance. Bot. Rev. 34: 17 - 34.

Sweet, A. & Hills, L.V 1971. A study of Azolla pinnata R. Brown. Amer. Fern J. 71: 1 - 13, pl. 1 - 4.

Genera in Australia and Papuasia

A family of a single genus ... Azolla (1)

Note

For convenience, some authors place both Azolla and Salvinia in the Salviniaceae, but there are substantial differences between the two families.


Updated November 1999 by Jim Croft (jim.croft@environment.gov.au)